In biology, a leg is the part of an animal's body (most commonly in one of the even numbers of 2, 4, 6 or 8, and many more in millipedes) that separates the body from the ground and is used for locomotion.

In an extended sense, a leg is any part of an object that connects it with the ground. An example is the legs of a table or a chair.

Strictly speaking, in human anatomy, the leg only includes everything between the knee and the foot, and is a part of the lower limb.